When you press the start button, a drawing of a WK2 and "QuadraDrive" appear in the EVIC for at least a few seconds.
In 2011 the ELSD was standard on all Overland V8s but in 2012 I think it was standard only on the Summit; It was included with the V8 Off-Road Adventure II Group on any model, however. At least thats what this page says, and they are typically accurate: http://wk2jeeps.com/wk2_2012_features.htm
ELSD makes a QTII into a QDII. You can also crawl under the rear end and look for an electric motor hanging off the driver's side of the diff housing. The electric motor drives the clutches.
If the 2012 Overland has the ORA II option package it should also have trail rated badge(s) and probably 18 inch wheels.